True. One could easily add a link between Y and another node in area 1 so
that doesn't happen. There could be a link between S and Y of greater cost
- so that Y tries to use S as a loop-free link-protecting alternate.

>>How about we look at it this way: what we're interested in is protection,
>>whether this is ECMP or LFA. Removing increased memory consumption from
>>consideration as something we'll have to deal with anyways: if an
>>implementation
>>is constrained to support N next-hops only, and all of the slots for a
>>route are
>>taken, well then one option is to not install LFAs at all--the route is

>>protected with ECMP after all. Should the topology change such that
some slots

>>become available--one can add LFAs there.
> True - but the ECMP may not give protection in the multi-area paths.
I'm sorry, I'm not sure I understand correctly what you mean here. Could you
explain, please?

Because the path in area 2 might cross back to area 1, the path in area 2
may not be link or node protecting with regard to the path in area 1. In
the above example, P2 offers node-protection, but not link-protection to
the path via P1. If a broadcast link (with the different costs) connected
S, P1 and Y, then P2 wouldn't be link-protecting either.